Scrutiny on hotel ventilation

Five of the nine cases of Covid-19 that have emerged in the community might have been prevented with better ventilation at managed isolation hotels, a public health expert believes.

As more information comes to light about Northland’s new case, health officials say the ventilation system at Auckland’s Pullman Hotel, where the woman stayed, is under scrutiny as a potential method of transmission.

A recent report released by Canterbury clinicians found poor ventilation was a factor in a situation where two PPE-clad health workers in Christchurch caught

Covid-19 from foreign fishermen. Talk about the role of ventilation systems is continuing to grow, sparked initially by a mysterious Covid cluster in Brisbane.

The Ministry of Health is now working to determine whether any of New Zealand’s 32 managed isolation and quarantine (MIQ) facilities need ‘‘additional filtration systems’’.

The University of Otago’s Professor Nick Wilson said shared airspace was a more likely explanation for two earlier cases of

Covid-19 that the ministry had said were probably due to surface transmission from a lift button and a rubbish bin.

‘‘Problems associated with walking through corridors with stale air or going in lifts . . . all that could be eliminated if people just stayed in their rooms.’’ Professor Nick Wilson, left

Those two cases, along with two health workers in Christchurch and potentially the latest Northland case, could mean there have been five instances of shared airspace transmission.

Wilson said the cases might have been prevented if ventilation systems were better. The ideal situation for good airflow in MIQ was pushing air out quickly while continually filling rooms with fresh air, he said.

Wilson said there needed to be more documentation on how many hotel rooms had windows that could be opened for natural airflow. He added that abandoning shared spaces could be one way to help. ‘‘Problems associated with walking through corridors with stale air or going in lifts ... all that could be eliminated if people just stayed in their rooms,’’ he said.

Pullman check fast-tracked Director-General of Health Dr

Ashley Bloomfield said yesterday that the transmission method for the Northland Covid-19 case remained unclear.

It could be down to respiratory droplets spread by close contact; transmission through the air, which potentially could include through ventilation systems; or transmission via a surface.

Health Minister Chris Hipkins said work was under way to see if additional filtration systems need to be installed on airconditioning units, ‘‘depending on the assessment of each of those facilities’’.

Airconditioning is different in each MIQ facility.

Bloomfield said that an assessment of ventilation at the Pullman Hotel would now be fasttracked.

He could not answer when asked whether the hotel floor the woman stayed on was sharing the same air between rooms, but said ventilation was considered when selecting a hotel for use as an MIQ facility.

A Ministry of Health spokesman later said that ventilation checks had been conducted in some MIQ facilities, without naming where.

‘‘Potential mitigations’’ to address the risk of airborne transmission were being considered, he said.

Other countries have invested heavily in improving ventilation systems as a way to combat the virus.

In Germany, about NZ$846 million has been invested for ventilation upgrades to public buildings, such as universities, the BBC reported.

CDHB report urges review

A recently released report by the Christchurch District Health Board found two health workers who caught Covid-19 from foreign fishermen in quarantine were most likely infected in the hotel corridor or at the room door of a highly infectious case.

In either scenario, transmission occurred ‘‘within minutes’’ of a room door opening.

The report reviews the clinicians’ experiences from an outbreak in Christchurch’s Sudima Hotel in October and November last year, when 235 foreign fishermen were staying. Thirty-one contracted Covid-19.

Both staff members who tested positive had a 1 per cent to 2 per cent chance of getting infected and were both wearing full personal protective equipment (PPE).

‘‘The high burden of infectious cases in the Sudima at the same time substantially increased opportunities for transmissions events to staff during routine interaction,’’ the report says. When the two health workers are thought to have got infected, other staff members were present.

The report notes it was possible that rooms of ‘‘highly infectious cases’’ may have been contaminated with infectious airborne Covid microdroplets, particularly in rooms with airconditioning turned off.

Among the recommendations is a complete review of ventilation specifications in all quarantine wings and facilities.

‘‘Assessment of opportunities to reduce risk by improving ventilation . . . is required,’’ the report concludes.